This application responds to RFA-MH-12-050 Optimizing Fidelity of Empirically-Supported Behavioral Treatments for Mental Disorders. There is a critical need to disseminate effective psychosocial treatments for mental disorders as there is a significant gap between evidenced-based approaches and common clinical practice. One factor that contributes to this gap is low therapist fidelity to manualized treatments in clinial settings. Anorexia Nervosa (AN) is a serious disorder associated with significant psychiatric and medical morbidity, mortality, and high treatment costs. The only evidence based treatment available for adolescent AN is Family-Based Treatment (FBT). However, the role of key components of FBT that lead to clinical success (e.g., promoting parental alliance, externalization, use of a family meal, and psycho-education about the life-threatening nature of AN), have not been evaluated in relation to outcome. Moreover, it is important that more efficient training strategies be developed to promote adoption of evidence based treatments. Although therapists can likely be trained to use FBT, the key interventions needed, the most reliable methods for assessing these interventions, efficient strategies for identifying fidelity, he relationship of fidelity to outcome, and how best to train therapists efficiently in FBT are all unanswered questions. To address these gaps in knowledge, we propose the following aims in a 2-Phase design. In Phase 1 (R21): 1) To refine an existing fidelity assessment instrument for FBT and examine its psychometric properties; 2) To examine the relationship of FBT fidelity and its components to patient outcome; 3) To explore predictors of fidelity in FBT; 4) To develop a Focused Training (FT) and supervision program for FBT. During Phase 2 (R33) we plan to 1) To assess the feasibility of conducting a comparison study of two types of training in FBT by conducting a small pilot RCT of FT versus Standard Training (ST); and, explore the comparative outcomes of the patients treated by therapists in each group. To accomplish the aims of Phase 1 (R21) we will code and analyze archival data from tapes selected from previous studies using FBT. During Phase 2 (R33) we plan to compare FT to ST by randomizing 30 therapists (15 therapists with 3 subjects nested in each therapist) to receive either one of the two training programs. The primary outcome will be feasibility (e.g., recruitment, attrition, assessment battery, resource costs) to conduct a sufficiently powered comparative study.